Hermetically-enclosed refrigerating machine



June 8, 1965 K. RoELsGAARn 3,187,992

` HERMETICALLY-ENCLOSED REFRIGERATING MACHINE.

Fled Nov. 27, 1961 2 Sheets-Sheet l June 8, 1965 K. RoELsGAARD HERMETYICALLY-ENCLOSED REFRIGERATING MACHINE:-

2 Sheets-Sheet 2 Filed NOV. 27, 1961 United States Patent O 3,187,992 HERMETCArLLY-ENQLSED REFRESERATING MACHINE Knud Roelsgaard, Nordborg, Denmark, assigner to Danfoss ved ing. M. Clausen, Nordborg, enmarir,

a company of Denmark Filed Nov. 27, 1961, Ser. No. 175,464 Claims priority, application Germany, Nov. 2o, 196), D 34,828 14 Ciaims. (Cl. 230-58) This invention relates to a hermetically-enclosed refrigerating machine in which the internal chamber of the capsule enclosing the machine is under pressure.

In the interior of the capsule of hermetically-enclosed refrigerating machines heat is generated at the windings of the driving motor, by the compression of the refrigerant gas, and as a result of friction in the machine parts. In particular, modern hermetically-enclosed refrigerating machines are, because of the requirement for the lowest possible noise level, spring mounted inside the capsule, and therefore they have a very poor thermal connection to the wall of the capsule. It is, for this reason, diicult to carry away the heat generated inside the capsule. Increased temperatures in the capsule as a result of the accumulation of the heat generated are not only dangerous from the standpoint of the electrical parts ofthe compressor, but they also lower the viscosity of the lubricating oil to a substantial extent. In addition, the vapor of the refrigerant becomes super-heated because of the higher capsule temperature, thus decreasing the compressor capacity. Heretofore, these drawbacks have been counteracted to some extent by means of secondary precautionary steps, such as increasing the removal of the heat by means of oil coolers disposed outside the capsule, or by atomizing the oil to cause the oil mist to adhere to the capsule wall and thus be cooled. It has also been suggested to form the capsule with a double wall, the lower part of which forms the condenser. All of these expedients however, are complicated and require relatively complex structures, and involve substantially higher construction costs.

It is accordingly an object of the present invention to provide means for removing the heat normally generated in a hermetically-enclosed refrigerating machine which avoids the drawbacks and disadvantages of prior constiuctions for such heat removal.

In accordance with the invention, those parts of the refrigeration unit which are disposed in the interior of the capsule and which conduct lthe cooling medium under compression pressure are provided with means for suppressing emission of heat to the interiorof the capsule. Thus, according to the invention, the capsule temperature is decreased by means of a reduction in heat emission interiorly of the capsule itself in contrast to known methods which involve forced cooling.

In one embodiment of the invention, the pressure line of the refrigeration unit is provided with heat insulation. Such a construction, according to the invention, is particularly effective when the exterior of the pressure line is provided with means which hinder gas flow and oil condensation which would tend to cause heat transmission.

In accordance with a further characteristic of the invention, the muler or silencer in the pressure line can form part of the pressure line. Because the muffler in the pressure line has a rather large surface, and is thus a rather large heat emitting member, the insulation of the muiiler in connection With the insulation of the pressure line is 'of great importance. Even in the case when only the muflier in the pressure line is insulated, a significant reduction in the capsule temperature will be brought about. The pressure line is positioned in the unit externally of the oil in a crankcase portion of the capsule or hermetic casing of the refrigeration compressor.

Other objects and features of the invention will be apparent from the following detailed description of illustrative embodiments taken in connection with the accompanying drawings, wherein,

FIG. 1 is a longitudinal cross-sectional view of a hermetically-enclosed machine embodying features of the present invention;

FIG. 2 is a top plan View of the assembly shown in FIG. l but with the cover of the capsule removed;

FIG. 3 is a cross-sectional view of an embodiment of a heat insulation according to the invention; and

FIG. 4 is a similar view of another embodiment of a heat insulation according to the invention.

Referring to the drawings, the machine illustrated and designated generally by the reference numeral 1, is mounted by means of springs 4 interiorly of a hermetic sealed casing or capsule 2 which is provided with a cover 3, all in conventional manner. The springs 4 are secured to the supporting element 5 for the motor stator 7, the element 5 being provided with a bearing for the vertical crank shaft 6 of the motor. The shaft 6 supports the rotor (not shown) of the electric motor. The compressor cylinder 8 is disposed and secured above the stator-supporting element 5.

The cylinder S receives the piston 9 which is actuated by the crank pin 11 through the crank rod 10. The valve separator plate 12 is disposed at the upper dead center point of the piston and carries the suction and pressure valves, which, however, are not visible. The two valve chambers, together with their associated outlet lines, are disposed in the cover plate 13. The portion of the machine just described forms no part of the present invention and can be of known construction. From the pressure outlet of the cover plate 13 a tube 14 leads to a muiiier 15 in the pressure line which, by means of a connector i6, communicates with a circular sinuous line 17. By reason of this construction, the pressure line can easily equalize the movements which occur between the cylinder assembly and the pressure line passage unit 18 in the capsule Wall. In FIG. 1 part of the connector 16 has been omitted so that the inlet 14 can be sho-wn.

According to the invention, the hot gas pressure line, or conduit means, i.e. the entire assembly 14 to'l7, or part of it, is provided with means for reducing heat emission. One embodiment of this means is shown in FIG. 3 wherein the pressure line tube section i7 is shown as being provided with its own insulation. By reason of this insulation, the heat from the rather warm refrigerant, which is under compression pressure, cannot be transmitted to the interior 4of the capsule and thereby to the cooling medium which is under suction pressure.

A like result is obtained with the construction shown in FIG. 4 wherein the sinuous section 17 of the pressure line is surrounded by an insulating foil sealed sleeve or envelope Ztl, which, in the embodiment illustrated, is formed from two foil sheets suitably joined together. It is advantageous to join the two foil sheets together along marginal edge portions for example along their edges 21. In this case, also, heat transmission between the refrigerant which is under compression pressure and the cooling medium which is under suction pressure is reduced because the latter cannot cause condensation on the line 17. Even the heat loss through the oil is reduced considerably as a result of this foil wrapping.

The mutl'ler can also be provided with insulation in the manner shown in FIG. 3 or FIG. 4. Due to the placement of the muflier in the pressure line there is no danger that heat loss will occur because of heat transfer to the cylinder structure, so that the larger part of that heat which the refrigerant previously emitted into the interior of the capsule, new will be emitted outside the capsule, whereby aisance the internal capsule temperature will be considerably re- Y duced.

The placing of the muffler in the pressure line has the further advantage that the entire cylinder assembly is available for placing silencer chambers for the suction pressure so that a better cooling of the cylinder is thus obtained, and by connecting several silencer chambers in series to the suction line, a very low frequency limit can be achieved.

`All materials which have heat insulation properties and which are also resistant to refrigerant and yoil can be utilized as the heat insulation i9 or as the foil material 2d.

The material must also not lose its strength as a result of continuous vibration or motion because breaking apart of the insulation can have an adverse effect upon the function and eiiiciency of the capsule. As the heat insulation i9, a porous material is preferably utilized. Especially suited for this purpose isa terephthalic acid polyester.

As previously indicated, the motor and the compressor per se are not part of the present invention and they can be of conventional construction, such to the structural changes relating to heat removal described and illustrated which are characteristic of the present invention. A typical motor compressor in which the present invention can be embodied is described, for example, in US. Patent No. 2,312,596. example, of the construction shown in my ctn-pending application led November 13, 1961 entitled Lubricating Device for a Motor Compressor.

lt will also be understood that various changes and modifications may be made in the embodiments described above and illustrated in the drawings without departing from the scope of the invention as dened in the appended claims.

it is intended, therefore, that all matter contained in the foregoing description and in the drawings shall be interpreted as illustrative only and not as limitative of the invention.

I claim:

1l. In a refrigerator unit, the combination of a hermetically sealed chamber having a wall with anouter heat-radiating surface, a motor-compressor unit in said chamber, means resiliently supporting said motor-compressor unit to provide a cushioned support permitting movement of said motor-compresor unit in said chamber, oil in said chamber for lubricating and cooling said motorcompressor unit, an inlet for refrigerant intoV said chamber, a pressure line for compressed refrigerant extending fom said compressor through said chamber wall to the exterior of said chamber, said line comprising a length of ilexible tubing inside said chamber permitting movement of said motor-compressor unit on its cushioned support by flexing of said tubing, and aheat insulating means covering on said tubing to inhibit the transfer of heat from the hot compressed refrigerant in said pressure line to the refrigerant and oil in said chamber, said insulating means being iiexible to permit the flexing of said tubing and being resistant to deterioration by said refrigerant and oil and the effects of vibration.

2. A refrigerator unit according to claim ll, in which said tubing is sinuous and in which said insulating means follows the sinuousity of said tubing.

.3. A refrigerator unit according to claim l, in which The motor and compressor can also be, for

said tubing is sinuous and said insulating means comprises oppositesheets of insulated material joined at their edges and enveloping the convolutions of said tubing.

4. A refrigerator unit'according to claim 1, in which said insulating means comprises porous material.

5. A refrigerator unit according to claim 4, in which said porous insulating material is a terephthalic acid polyester.

6. A refrigerator unit according to claim 1, in which said pressure line further includes a Inuilier connected with said tubing and in which said mufer is covered with a heat insulating means resistant to deterioration by said refrigerant and oil.

7. In a hermetic compressor, a hermetic-sealed casing, a compressor in said casing for compressing a gaseous medium, said casing containing discharge hot gas conduit means connected to said compressor for discharging said gaseous medium from said casing after compression in said compressor, said conduit means having a configuration to allow expansion and contraction of said conduit means in operation, insulation internally lof said casing covering said conduit means to reduce heat transfer from said conduit means and hot gas therein into the interior lof said casing.

8. In a hermetic compressor according to claim 7, in which said gaseous medium is a refrigerant convertible to a liquid phase.

9. in a hermetic compressor according to claim 7, in which said insulation comprises means to allow expansion and contraction of said conduit means Without detriment to the insulation.

lil. In a hermetic compressor according to claim 7, in which said conduit means comprises a sinuous conduit, and in which said insulation com-prises an envelope con figuration in which sinuous conduit is contained.

lill. In a hermetic compressor according to claim lill, in which said insulation comprises insulation sheet material sealed along Imarginal edge portions thereby dening said envelope configuration.

12. In a hermetic compressor according to claim 7, in which said casing comprise a crankcae portion containing a liquid lubricant in operation, and in which said conduit means and insulation interiorly of said casing are disposed externally of the lubricant.

`13. In a hermetic compressor according to claim 7', in which said insulation comprises a material chemically inactive with materials contained in said casing.

M. ln a hermetic compressor according to claim 7, in

- which said conduit means comprises a muiier and in which said insulation insulates said muer.

References Cited by the Examiner Y UNITED STATES PATENTS 2,084,341

McCloy 230-232 KARL I. ALBRECHT, Primary Examiner.

LAURENCE V. EFNER, JOSEPH H. BRANSON, In.,

Examiners. 

1. IN A REFRIGERATOR UNIT, THE COMBINATION OF A HERMETICALLY SEALED CHAMBER HAVING A WALL WITH AN OUTER HEAT-RADIATING SURFACE, A MOTOR-COMPRESSOR UNIT IN SAID CHAMBER, MEANS RESILIENTLY SUPPORTING SAID MOTOR-COMPRESSOR UNIT TO PROVIDE A CUSHIONED SUPPORT PERMITTING MOVEMENT OF SAID MOTOR-COMPRESSOR UNIT IN SAID CHAMBER, OIL IN SAID CHAMBER FOR LUBRICATING AND COOLING SAID MOTORCOMPRESSOR UNIT, AN INLET FOR REFRIGERANT INTO SAID CHAMBER, A PRESSURE LINE FOR COMPRESSED REFRIGERANT EXTENDING FORM SAID COMPRESSOR THROUGH SAID CHAMBER WALL TO THE EXTERIOR OF SAID CHAMBER, SAID LINE COMPRISING A LENGTH OF FLEXIBLE TUBING INSIDE SAID CHAMBER PERMITTING MOVEMENT OF SAID MOTOR-COMPRESSOR UNIT ON ITS CUSHIONED SUPPORT BY FLEXING OF SAID TUBING, AND HEAT INSULATING MEANS COVERING ON SAID TUBING TO INHIBIT THE TRANSFER OF HEAT 